京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20882号 / 理博第4334号 / 新制||理||1623(附属図書館) / 京都大学大学院理学研究科数学・数理解析専攻 / (主査)教授 加藤 毅, 教授 上 正明, 准教授 入谷 寛 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

In this dissertation, a new numerical method for solving some problems on the semiinfinite domain is presented. The method is based upon the modified rational Bernoulli functions. These functions are first introduced. Operational matrices of derivative and product of modified rational Bernoulli functions are then derived and are utilized to reduce the solution of the equations to a system of algebraic equations. This method is used to solve the following problems: Lane-Emden type equations, Volterra’s population model, Blasius equation, and MHD Falkner-Skan equation. Illustrative examples are included to demonstrate the validity and applicability of the technique.

Många unga vuxna använder sig av sociala medier innan de ska sova för natten. Majoriteten av dessa sociala medier använder funktionen ”infinite scroll”, ett oändligt flöde som är designat i syfte att förlänga användarens tid på plattformen. Samtidigt är det många unga vuxna som upplever att de inte får tillräckligt med sömn. Denna studie utgick från frågeställningen “hur sömnkvalitet hos studenter påverkas av att använda sociala medier med oändliga flöden innan läggdags”. Detta undersöktes med hjälp av tre olika metoder för att bedöma sömnkvalitet. Tidigare forskning på området har funnit samband mellan sömnstörningar och volymen sociala medier som konsumeras innan läggdags. I denna studie undersöktes om liknande samband kan finnas hos specifikt sociala medier med oändliga flöden. Undersökningen pågick under två veckor och var uppdelad i en normalvecka och en vecka där studiedeltagarna inte fick använda sociala medier med oändliga flöden innan läggdags. De tre olika metoderna för att bedöma sömnkvalitet innefattade att studiedeltagarna varje morgon bedömde sin sömn på en femgradig skala, loggade sin sömn med hjälp av sömnanalysapplikationen Sleep Cycle varje natt och besvarade en enkät baserad på Pittsburgh Sleep Quality Index (PSQI) i slutet av varje vecka. Resultatet visade att användningen av sociala medier med oändliga flöden generellt sett endast var en liten andel av studiedeltagarnas totala användningen, och att det istället var videoapplikationer som användes mest extensivt innan läggdags. De tre metoderna indikerade på olika resultat. PSQI visade på att sömnkvaliteten blev bättre när sociala medier med oändliga flöden uteslöts. De dagliga bedömningarna visade inte på några större skillnader i sömnkvalitet mellan veckorna. Sleep Cycle visade å andra sidan att de flesta studiedeltagare hade en sämre sömnkvalitet den andra veckan. Studien tyder på att det är flera faktorer som påverkar sömnen vilket gör den komplicerad att undersöka. Dessutom har de faktorer som påverkar sömnen olika inverkan på demetoder som bedömer sömnkvalitet. Majoriteten av tidigare forskning kretsar kring självbedömningar och uppskattningar, något som i denna undersökning försökte kompletteras med hjälp av mer okonventionella metoder. De motsägande resultaten kan bland annat förklaras av metodernas tillförlitlighet och studiedeltagarnas oväntade vanor kring deras mobilanvändning. Utifrån resultatet väcktes frågan om att det inte är vilken typ av sociala medier som används, utan snarare hur dem används, som påverkar sömnkvaliteten. / Many young adults use social media before bed. The majority of social media have adopted “infinite scroll”, endless feeds that are designed to prolong the user’s sessions on the platform. Simultaneously, many young adults experience insufficient sleep. This study examined “how sleep quality in students is affected by the use of social media with infinite scroll before bed”. This was examined using three different methods of assessing sleep quality. Previous research in this field found connections between sleep disturbances and the usage of social media before bed. Therefore, this study examined if similar connections exist in specifically social media with infinite scroll. The study was conducted over a two week period and was split into one regular week and one week where social media with infinite scroll was unallowed before bed. The three different methods for assessing sleep quality consisted of the study participants evaluating their sleep on a five-point scale every morning, logging their sleep using the sleep analysis application Sleep Cycle every night, and answering a questionnaire based on the Pittsburgh Sleep Quality Index (PSQI) at the end of each week. The results show that there generally was no extensive usage of social media with infinite scroll among the study participants. Instead, the majority of study participants used video applications more before bed. The three different methods indicated contrasting results. PSQI showed that the sleep quality improved when social media with infinite scroll were excluded before bed. The daily assessments did not show any major differences in sleep quality between the weeks. Sleep Cycle, on the other hand, showed that most study participants experienced worse sleep quality in the second week. The study found that there are several factors affecting sleep which makes it complicated to examine. Additionally, the factors that affect sleep could have differentimpact on themethods that assess sleep quality. The majority of previous research was conducted using self- assessments and estimations, something that this study tried to complement with the use of unconventional methodology. The conflicting results can partly be explained by the reliability of the methods and the study participants' unexpected smartphone habits. Following the results, the question was raised whether it is the type of social media, or rather how social media is used, that impacts the sleep quality.

A database containing Henry's law constants, infinite dilution activity coefficients and solubility data of industrially important chemicals in aqueous systems has been compiled. These properties are important in predicting the fate and transport of chemicals in the environment. The structure of this database is compatible with the existing DIPPR® 801 database and DIADEM interface, and the compounds included are a subset of the compounds found in the DIPPR® 801 database. Thermodynamic relationships, chemical family trends, and predicted values were carefully considered when designating recommended values. Henry's law constants and infinite dilution activity coefficients were measured for toluene, 1-butanol, anisole, 1,2-difluorobenzene, 4-bromotoluene, 1,2,3-trichlorobenzene, and 2,4-dichlorotoluene in water using the inert gas stripping method at ambient pressure (approximately 12.5 psia) and at temperatures between 8°C and 50°C. Fugacity ratios, required to determine infinite dilution activity coefficients for the solid solutes, were calculated from literature values for the heat of fusion and the liquid and solid heat capacities. Chemicals were chosen based on missing or conflicting data from the literature. A first-order temperature-dependent group contribution method was developed to predict Henry's law constants of hydrocarbons, alcohols, ketones, and formats where none of the functional groups are attached directly to a benzene ring. Efforts to expand this method to include ester and ether groups were unsuccessful. Second-order groups were developed at a reference condition of 298.15 K and 100 kPa. A second-order temperature-dependent group contribution method was then developed for hydrocarbons, ketones, esters, ethers, and alcohols. These methods were compared to existing literature prediction methods.

In calculus the concept of an infinite derivative – i.e. DF(x) = ±∞ – is seldom studied due to a plethora of complications that arise from this definition. For instance, in this extended sense, algebraic expressions involving derivatives are generally undefined; and two continuous functions possessing identical derivatives at every point of an interval generally differ by a non-constant function. These problems are fundamentally irremediable insofar as calculus is concerned and must therefore be addressed in a more general setting. This is quite difficult since the literature on infinite derivatives is rather sparse and seldom accessible to non-specialists. Therefore we supply a self-contained thesis on continuous functions with infinite derivatives aimed at graduate students with a background in real analysis and measure theory.  Predominately we study continuous primitives which satisfy the Luzin condition (N) by establishing a deep connection with the strong Luzin condition – a weak form of absolute continuity which has its origins in the Henstock–Kurzweil theory of integration. The main result states that a function satisfies the strong Luzin condition if and only if it can be expressed as a sum of two such primitives. Furthermore, we establish some pathological properties of continuous primitives which fail to satisfy the Luzin condition (N).

This thesis investigates the validity of the standard thermal response test (TRT) results when performed on a series of boreholes (string). The typical TRT consists of subjecting a single borehole to a constant heat injection rate to obtain the temperature response in the ground which can then be used to determine the ground thermal conductivity. When completed on a single borehole, the results may be analyzed with the line source theory, since the assumption of a single line heat source is valid. For multiple boreholes, the assumption of a single line source becomes invalid if the spacing between the boreholes is small enough for borehole thermal interaction to occur. Moreover, for boreholes that are charged in series, heat transfer from the horizontal pipes that connect the vertical boreholes may also influence the ground thermal response. This thesis takes an in-depth look at the different factors that affect the results of TRTs performed on borehole strings. Different analysis methods are implemented to determine areas of improvement for determining the thermal conductivity of the soil surrounding the borehole string. For the analysis, the infinite line source (ILS) model and a model developed using TRNSYS 18 were used to determine the effective thermal conductivity. The results show that TRNSYS is unable to accurately model a TRT performed on a borehole string. The horizontal pipe model within TRNSYS proved to have significant fundamental issues, as the effective thermal conductivity is greatly underestimated with values of 1.2±0.1W/mK and the results of increasing the horizontal length both increased and decreased the effective thermal conductivities. The results from the ILS demonstrate that an effective thermal conductivity of 1.7±0.2W/mK is an appropriate estimate of the soil at the BTES field tested, as the borehole string with the furthest spacing between boreholes gave an effective thermal conductivity of 1.7W/mK. Performing multiple thermal response tests within the same BTES field also provided evidence of the need to implement multiple TRTs as common practise. The testing presented shows that the effective thermal conductivity can vary within ±0.2W/mK within the same relative location. With better knowledge of the thermal properties within the BTES field location comes the opportunity for improved planning of operation and control of thermal distribution within the field. This would be especially beneficial when dealing with seasonal BTES fields / Thesis / Master of Applied Science (MASc)

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